The invention relates to improvements in a ply or wrapped yarn spinning assembly with a drawing mechanism for drawing sliver, at least one hollow spindle arranged downstream of the drawing mechanism with a bobbin with binding thread placed thereon for binding the sliver to form ply yarn, a pair of take-off rolls for the ply yarn, and a windup (take-up) device for the ply yarn, as well as drive means for these component parts and a thread monitoring device which upon a disturbance in the spinning operation automatically interrupts the drive mechanisms for the component parts arranged downstream of the drawing unit.
Ply yarn spinning assemblies of this general type have been contemplated, such as shown in German Unexamined Laid Open Application (DOS) No. 2,753,349. In the previously contemplated types of construction, the provision is made to automatically arrest the impaired spinning station in case of thread break while all other spinning stations of the machine continue operation. For this purpose, the bundle of spinning fiber exiting from the drawing unit is seized by a suction tube and deflected from its travel direction. At the same time, a thread monitor is swung away due to the fading thread tension and closes contact with a switch interrupting several drive mechanisms.
Thus, on the one hand, the drive of the hollow spindle is interrupted by the feature that a solenoid-operated device lifts the driving tangential belt off the spindle and applies a brake. Furthermore, the pressure roll of a pair of take-off rolls is lifted off the drive roll, likewise by way of solenoid operation. Finally, a plunger is provided which lifts the windup bobbin off its drive roll, likewise under the action of a solenoid. Operation is resumed in such types of construction by pneumatic means, especially by the connection and disconnection of suction streams which combine the individual thread components and rethread same into the spinning unit.
A disadvantage of the above noted previously contemplated types of construction resides in that the shutoff operation due to thread break functions only if the breaking site lies between the exit from the drawing unit and the entrance into the hollow spindle. Only in this case is it possible to remove by suction the sliver which is still being fed from the drawing unit. If the thread break occurs at some other location, for example downstream of the hollow spindle, then the sliver feed into the hollow spindle is continued. With the spindle speeds nowadays customary, about 30,000 per minute, and production rates of about 200 meters/minute, this can result in grave damage to the spinning assembly. Even if the sliver supplied by the drawing unit is properly removed by suction, a relatively high loss of material occurs for the aforementioned reasons, because the sliver is removed by suction until the disturbance at the respective spinning station has been eliminated. Another disadvantage is that the solenoids (electromagnets) provided in the conventional machine for operating the shutoff process represent units which are operable independently of one another and which are relatively expensive and can show impairment of their function individually, which then leads to a disturbance of the entire procedure. Also the operating safety of such electrically operated drive elements requires constant servicing thereof.
Therefore, it is an object of the present invention to construct a ply yarn spinning machine in such a way that, in case of disturbance, the individual shutoff of the impaired spinning assembly becomes possible in a very simple way, without the occurrence of subsequent damage and loss of production in case of such a disturbance. Also, a possibility is to be provided in especially preferred embodiments for operating all individual assemblies safely and in dependence upon one another during the shutdown step--and also during the subsequent restarting step.
This above noted object has been attained by associating with the drawing unit a mechanical operating means for swinging open the load-bearing means, which operating means is triggered in case of a breakdown by the thread monitoring device. This arrangement has the advantage that, in case of a mishap, not only is the drive of the subsequently disposed component parts interrupted but also the assembly feeding the sliver is arrested so that loss of spinning material can be avoided. Also, ensuing damage by additionally fed fiber material is thus avoided with certainty. The arrangement of this invention also has the advantage that a very simple mechanical operation becomes possible which advantageously can furthermore be designed in such a way that also for interrupting the drive mechanisms of the other subunits it is possible to provide a corresponding, or even the same, mechanical operating means. It is especially advantageous for this purpose to equip all subunits with drivable parts which can be swung away from constantly revolving, driven parts, so that then the mechanical operating means can consist, for example, of an operating rod actuatable by way of pressure cylinders according to especially preferred embodiments. This arrangement, besides exhibiting a simple mechanical structure likewise ensuring a safe and readily controllable functioning, also has the advantage that the precondition is provided for being able to start up the spinning station in synchronism after elimination of the breakdown.
An especially simple, but effective, preferred design is obtained by associating the operating rod guide means for interrupting the drive mechanisms of the hollow spindles, of the pair of take-off rolls, and of the windup device. Such guide means are preferably fashioned as guide pins in an especially simple way, which guide pins control respectively one lever arm fashioned as a leaf spring and respectively attached to the component of the individual assemblies which can be pivoted away from the drive means. This construction has the advantage that the leaf springs can be slidingly guided between guide pins in an especially easy fashion, but that, on the other hand, these leaf springs can also provide the required pretensioning to be able to urge the respective unit against the drive means in the operating condition.
In an advantageous preferred embodiment, two series-arranged hollow spindles are provided which are configured to be swung away from the respective drive belt with their drive whorls. The series connection of two hollow spindles makes it possible to increase production. The swinging away of the hollow spindles offers the advantage, besides the interruption of the drive, that the bobbins enter into a position favorable for controlling the binding thread during changing of the feed bobbin.
In a further development of preferred embodiments, the provision is made that the windup device comprises a drive roll and, at a radial spacing therefrom, a grooved roll, both of which are in engagement with a drive-transmitting friction pressure roll, which latter is configured to be swung away from the grooved roll. It is thereby possible to interrupt the drive for the windup device without having to lift the windup roll proper off the grooved roll. For a lifting off of the windup roll is problematic inasmuch as, on the one hand, the bobbin arm must traverse differing distances--due to the varying bobbin diameters possible--and, on the other hand, the measure provided in conventional spinning assemblies has the effect of squeezing the thread laps of the windup bobbin, which is not the case here due to the novel construction.
To fashion the monitoring process especially effective, the provision is made in preferred embodiments, that respectively one thread monitor is arranged between the drawing unit and the hollow spindle, as well as between the hollow spindle and the pair of take-off rolls. In this way, the monitoring step not only covers the thus-produced entire thread--which due to a reduction in tension already responds if only one component is broken--but additionally covers the sliver exiting from the drawing unit.
In a further embodiment of the invention, each hollow spindle is associated with a preferably optical device for scanning the degreee of fullness of the bobbin for the binding thread. It is important to monitor the degree of fullness of the binding thread bobbin, because trouble also occurs, after all, if the binding thread bobbin no longer supplies any thread. The optical monitoring of the binding thread bobbin suitably utilizes the differing reflective characteristic at the hollow spindle since--depending on whether or not the feed bobbin still contains a thread--a light beam emanating from the thread monitor will be differently reflected.
To restart the spinning assembly, a bobbin with an auxiliary thread is provided in accordance with especially preferred embodiments of the invention. Thereby the piecing operation is substantially facilitated. If no auxiliary thread were used, there would be the danger that the still untwisted sliver during startup is immediately broken again at the critical point upon entrance into the hollow spindle. The auxiliary thread naturally exhibits an increased strength and serves temporarily as a guide means for the remaining components. The pneumatic units for piecing purposes as they are arranged in previously contemplated types of construction can be omitted.
It is advantageous to feed the auxiliary thread to a suction removal device arranged in the zone of the windup means but in such a way that the auxiliary thread does not pass on to the windup bobbin. It is ensured in this way that neither the auxiliary thread nor the piece of yarn, which deviates in quality during the piecing operation from the quality obtained during normal operation, can enter the normal bobbin.
It is advantageous to associate with the auxiliary thread, after the bobbin as well as in front of the suction removal means, a cutting device according to preferred embodiments. It is possible in this way to remove the auxiliary thread again after the piecing operation has been completed, whereupon the normal ply yarn can be fed again to the windup bobbin.
In an advantageous embodiment of the invention, the drawing unit, the spindles, the pair of take-off rolls, and the windup device are arranged to be started up simultaneously. With the use of an automatic piecer, it is possible by this measure to do without an auxiliary piecing thread. Since the take-off rolls and the windup device attain full speed more rapidly than the spindles, it is advantageous herein to provide that the whorls of the spindles come into engagement with the drive belt somewhat earlier than the remaining elements to be driven.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.